


onion-san(s)

by I_Write_Sans_Not_Tragedies



Category: Undertale (Video Game)
Genre: M/M
Language: English
Status: Completed
Published: 2016-06-11
Updated: 2016-06-11
Packaged: 2018-07-14 08:36:29
Rating: Explicit
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 2,073
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/7162661
Author URL: https://archiveofourown.org/users/I_Write_Sans_Not_Tragedies/pseuds/I_Write_Sans_Not_Tragedies
Summary: <blockquote class="userstuff">
              <p>Sans is one kinky motherfucker. He's seen some of Alphys's more "explicit" anime videos. An agreement composed of pure sin is the result.</p>
            </blockquote>





	onion-san(s)

**Author's Note:**

> EDIT: I moved this from my main ao3 (Spectascopes) because... it seems more appropriate for this account. I'm very sorry, I still think this is hilarious lmfao, it's the first full-fledged porn i ever posted!
> 
> This started off as a hilarious joke but then it became an actual porn fic of Sans and Onion-san. I did my best, but I'm not an nsfw writer, please be gentle.

 

They met there every few weeks. Life in Snowdin could be boring when you were as nihilistic as Sans was. He was always happy to hang out with Papyrus and watch him get up to his usual mischief, but he could never involve his wonderful brother in anything lewd in the slightest. While he knew that it was likely going to happen someday, the thought of Papyrus doing anything sexual made Sans want to vomit and then start crying. It wasn't a healthy response, but, he couldn't help it.

So Sans took his business elsewhere. Waterfall as a good place to be alone when you wanted to be, if you only knew where Undyne wasn't. Where Sans went, most people avoided. He didn't worry one bit about being found when his company was so... ah, difficult to swallow.

For all of the short skeletons bad traits, his fucked up kinks might've been the worst and most disturbing. He walked into the dimly lit room and heard the gentle moving of water. He felt a blush rise to his cheeks at the mere sight of the room. By association, he'd come to think of it solely in the sexual way. It wasn't like he came here to talk, after all.

He strolled to the long walkway that lead to the lone statue. He lit up his eye with blue magic to cast some light on the room. When he looked around, he didn't see anything except the slowly moving water and the sparkling crystals above. He set down his bag- filled with instant noodles and anime trash he'd collected at the dump in the last few weeks. He was about to call out when a flash of yellow shot out of the water and tripped him.

He landed on his ass with an 'oof' and heard a damn annoying laugh fill the room. He looked towards the source of the tentacle and saw Onion-san's sparkling eyes watching him. He grit his teeth but put on a smile.

“Heya, pal,” he said, but he and the onion monster both knew what Sans was there for.

“Didja bring me more neat stuff?” the monster cooed, grabbing the bag with two tentacles and sifting through it. Their eyes lit up when they pulled out an anime figure and held it aloft in their wavering arms.

“Wowie! This is a good one, ya hear?”

“Like it? I almost gave it to my bro, but I figured you'd appreciate it more,” Sans said. He stood by with his hands in his pockets as the weird monster continued to look through the bag with its tentacles, giving little 'ohs' and 'ahs' as it went. Even if Sans had been doing this for a few years, he always felt awful coming and literally buying tentacle sex from an annoying onion-shaped blob.

“Today'll be eeeextra special, Sansy!” Onion-san said as they took the bag and sat it aside. Without any warning or hesitation their tentacles were undressing the skeleton in a firm but gentle manner.

“Heh, what does that mean?” he asked, but he was blushing and trembling in anticipation and sort of guilt? He knew he was awful, though, and he loved this way too much to ever turn back.

“You tell me, Sansy! You're my big favorite. Whatever ya want, ya hear?”

Sans gulped. Onion-sans voice was absolutely the least sexy thing in the entire world, but he already knew he wasn't going to get any sort of lewd talk from the octopus. As he'd awkwardly established early on, Onion-san didn't feel arousal or sexual attraction. But apparently some people came into their hide-away and did some pretty nasty things before they knew the monster was in there, so Onion-san wasn't exactly innocent.

“Just the usual, pal. Tibia-honest, I'm not much for experimenting.” Sans laughed at his own pun, but Onion-san join in after a second.

“You got it, Sansy!” they said, and god damn they didn't waste one moment.

Sans felt slick tentacles pull his hoodie over his head and toss it onto the walkway a few feet back. The slight chill that hit his body made him shiver. Or maybe that was the tentacle that was slowly snaking underneath the band of his shorts to pull his pants down and smoothly off.

Onion-san didn't talk during any of it. That was the one condition Sans had to be strict about- that voice would absolutely ruin the moment and turn his hard-on into a hard-to-swallow situation.

Before long Sans was naked, sitting on his knees on the smooth rocky pathway. He faced away from Onion-sans body, because yet again, he couldn't enjoy himself if he was staring into the anime eyes of a fucking onion-octopus.

A tentacle nudged his wrist and he obediently put both above his head. He could barely feel the cold over his arousal as the appendage wrapped his hands together and held them over him. Droplets of water trickled down his arm, making him shiver, which only made him more turned-on. Onion-san was quiet. He did his best to forget that the monster was even there.

He felt exposed and vulnerable on the floor with so much open space around him. He was a kinky fucker, though, and it turned him on so fucking much.

He felt a slow appendage trail across the back of his ribs. It ran along each one individually before slipping into his rib cage and doing the same from the inside. Soon, another joined it. Sans hissed through his teeth at the intrusion. It felt so good, and it made the ache in his pelvis grow to a painfully pleasant level.

A third tentacle wound its way around his chest and was happy to wind and unwind while its brothers squirmed inside of him. He let out a small moan at all of the stimulation at once. He couldn't do this on his own. He needed more- his arms tried to shift in their bonds but the tentacles stopped him from doing anything more than tense and relax his lower body as the movement in his ribcage grew just a little faster with each passing minute.

“Ah...” he breathed as he watched the intruders inside of his chest. They'd avoided his soul until that point, but as the little moan escaped his mouth one of the yellow feelers flicked up and brushed the length of itself against the center of his being in one long and gentle stroke.

“Ohh fuck,” he breathed as he shoved his chest forward to prompt further attention. But as he did it the tentacle drew away and ran along his lowest rib, teasingly close to his sensitive spine. It trailed down and for a moment Sans breathed in anticipation. He wasn't expecting one of the two remaining tentacles to begin playfully stroking his soul. He froze and shifted into the touch as a long moan was drawn out of him.

“Oh god... oh, shit, that's good,” he whined. With one tentacle still inside of his ribs, one touching his soul, and one till stimulating his sternum and outer spine, he barely noticed that the fourth tentacle was nowhere to be felt. He let himself melt into the pleasure and relaxed into his bonds. When the fourth tentacle began to run slowly up and down the inner spine below his ribs, he could only let shallow breath and quiver at its touch.

He wanted more, but he wanted to savor this. It wasn't enough, it wasn't nearly enough, but he felt drool run down his chin as he let his head fall back and the little noises filled the empty cavern. When a tentacle would press into his soul and he'd buck his pelvis forward, he relished in not being able to move his arms. He most sensitive area was burning for attention. Onion-san withheld his touch, but the strokes against his soul were becoming more intense. Sans's breaths became shallow and the small moans that escaped him were humiliating. But Onion-san didn't say a word.

Sans bucked his hips forward, longing for friction against his pelvis, but the most he got was the tentacle sliding along his spine. Waves of pleasure coursed through him and he shifted his legs around in an attempt to get more purchase for his hips, but Onion-san lifted his arms higher above his head to prevent him from moving around.

“Ah... fuck, please...” Sans begged. He didn't have time to draw in a breath to beg again before another tentacle was pressing against his pelvis as the one on his spine wrapped tightly around to hold his lower body still.

“Ah... f-fuck, fuck, mmf,” he was cut off as one of the rub tentacles wrapped around his head and mouth. He was glad, because his moans were becoming more and more guttural and noisy. He breathed and whined into the appendage and rocked his hips forward into the tentacle on his pelvis. He wanted more.

Soon all but one of Onion-san's tentacles were on his body. He could barely tell what was being touched anymore. It was messy at first, just limbs sliding over him and touching him where they shouldn't be, with his pelvis attempting to create a rhythm. He could feel the pleasure beginning to pool at his center. The breaths that escaped around the tentacle were pants of pleasure mixed with spluttering gasps as the tentacles found new and exciting ways to penetrate and slide through his bones.

Sans wished he could say he lasted long, but in reality it couldn't have been more than twenty minutes. The movement against his sensitive crotch wasn't enough to reach climax, but it was so cruelly close that Sans was all but fucking the air in front of him in a desperate attempt to find release.

“Mmmpf- ffff.... ah-” Sans moaned into the appendage wrapped around his head. Onion-san must have recognized his growing need, because suddenly the tentacle pulled away from his mouth and wiped the drool off of his face, only to slither down his front and begin rubbing the very sensitive area at the bottom of this pelvis. He hips bucked forward sharply as a sharp yelp escaped his now-free mouth, and he found that the tentacle held its ground against his thrusts.

“God- oh fuck, yes, f-fuck, fff... ah.” Sans was so close to climax, but Onion-san knew that. When Sans would start thrusting too fast, the tentacles would pull away, and he would whine and feel like such an animal, on his knees bucking his hips into nothing but open air. Sweat dripped down his face and his spine and his legs were quivering and shaking.

“Please... p-please, fuck, just a little more,” he whined as the pushes against his soul and pelvis began to sync up. He bit down on a growing cry as he twitched and felt the orgasm begin to build. Drool was dribbling from his chin.

The tentacle near his soul moved faster, and soon the one at his crotch followed. His thrusts lost their rhythm and he gave a deep and raw moan as the pleasure built at his core.

“Fuck- fuck, I'm- nngh, gonna-!” he was cut off as the pleasure washed over and the orgasm hit him like a punch to the gut. He cried out and arched his back into the movements as he rode out the climax. The tentacles that fucked him began to slow as he gasped for breath and fell into his bonds with an exhausted sigh.

Onion-san released his spine, but the feelers still held his wrists as he panted for breath. They withdrew from his chest cavity, sliding across the slick bone as they went. Sans shivered and gasped as the one resting against his pelvis slowly fell away, trailing along the sensitive bone, leaving him hunched in over-stimulation.

Sans heaved a few labored breaths before his wrists were gently lowered to his lap and released. He watched them with hazy eyes, still bathing in the feeling of the long-awaited climax. He gulped and steadied himself before he tried to say anything.

“Fuck... that was... good,” he said. “Just... just give me a few minutes here. Shit.”

“Kay!” Onion-san chirped. Sans closed his eyes and just sort of accepted the shame that came with hearing the monster who'd just fucked him's voice.

If it meant sex like this, he'd deal with it.

 

**Author's Note:**

> The conversation was about Undertale, I said something about being Brash and Bold and then Squidward came up, and then porn came up, and this idea blossomed in my mind and before I could really think about NOT doing it I'd already started. Please forgive me. I can't kinkshame anybody anymore.


End file.
